Systems and methods for event tracking using time-windowed counters

ABSTRACT

Some embodiments include tracking events and classifying assets within a computer system. A time series of occurrences of an event type associated with at least one asset is generated. A first signal value and a second signal value is determined based on the time series. The at least one asset can be classified based on comparison of the first signal value and the second signal value. The time series can be based on at least one time window including time intervals. Counters to determine a number of occurrences of an event type can be associated with the time intervals. Each of the counters can be incremented upon occurrence of the event type associated with the at least one asset during an associated time interval.

FIELD OF THE INVENTION

The present invention relates to the field of social networking. Moreparticularly, the present invention provides techniques for trackingevents and classifying assets within a social networking system.

BACKGROUND

Internet social networks have become a significant phenomenon. Socialnetworks allow an Internet user to create an account and a user profile,often for free, and interact with other users of the social network. Asocial network user can gain access to the profile of another user byrequesting to add him or her as a friend. Once approved, the“friendship” typically gives both users access to each other's profilesand the content posted on them. Friends' posts may appear as newsstories in each other's news feeds, and friends can usually comment oneach other's news stories. Social network users typically seek toassemble a group of friends or followers with whom they interact.Information on a user's profile is often only accessible to the user'sfriends.

Social networks are providing users with increasingly sophisticatedfunctionality. Early social networks offered little more than a simpleinterface for users to communicate and post messages. Now, on manysocial networks, users may share numerous different types of content andinteract with each other's content in a variety of ways. A userinteraction may result in an event, i.e., an action that occurs withinthe social network. As social networks grow in size and complexity, thevolume and variety of events that occur within the social networks mayincrease exponentially. An operator of a social network may wish toupdate the features, functionality, and user interface of the socialnetwork based on the types and frequency of user interactions and otherevents. Moreover, an operator of a social network may wish to assessusers, content items, messages, and other assets based on the eventsinvolving them.

SUMMARY

To allow for tracking events and classifying assets within a socialnetworking system, embodiments of the invention include systems,methods, and computer readable media for event tracking usingtime-windowed counters. A time series of occurrences of an event typeassociated with at least one asset is generated. A first signal valueand a second signal value is determined based on the time series. The atleast one asset is classified based on comparison of the first signalvalue and the second signal value.

In an embodiment, at least one of the first signal value and the secondsignal value is based on uniqueness. In an embodiment, the time seriesis based on at least one time window including time intervals. In anembodiment, counters to determine a number of occurrences of an eventtype are associated with the time intervals. In an embodiment, each ofthe counters are incremented upon occurrence of the event typeassociated with the at least one asset during an associated timeinterval.

In an embodiment, the at least one time window is implemented as acircular buffer. The circular buffer may comprise elements representingthe time intervals. In an embodiment, a counter associated with a leastrecent time interval of the time intervals is reset, and the counter isincremented upon occurrence of the event type associated with the atleast one asset during a most recent time interval.

In an embodiment, the at least one time window is implemented as alinear buffer. The linear buffer may be associated with at least one ofexponentially-decaying time intervals and non-decreasing time intervals.In an embodiment, the linear buffer may comprise elements representingthe time intervals. In an embodiment, a value is provided from a firstcounter associated with a first time interval to a second counterassociated with a second time interval, the first counter is reset, andthe first counter is incremented upon occurrence of the event typeassociated with the at least one asset.

In an embodiment, a score is generated based on a procedureincorporating the first signal value and the second signal value and theat least one asset is assigned to a classification based on the score.In an embodiment, the procedure comprises at least one of a decisiontree and a machine learning model. In an embodiment, the classificationcomprises at least one of a spam category, a popularity category, and aranking.

In an embodiment, the determining comprises calculating an integral ofat least one function. In an embodiment, a policy is modified based onclassification of the at least one asset. In an embodiment, at least oneof the generating, the determining, and the classifying is performed inreal time.

Many other features and embodiments of the invention will be apparentfrom the accompanying drawings and from the following detaileddescription.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a network diagram of a system 100 for tracking events andclassifying assets within a social network in accordance with anembodiment of the invention.

FIGS. 2A-B are illustrations of an example graph including a time seriesof the number of times a URL has been shared within the socialnetworking system, in accordance with an embodiment of the invention.

FIG. 3 illustrates a process for classifying an asset in accordance withan embodiment of the invention.

FIG. 4A illustrates an example circular buffer representing a first timewindow and a series of counters in accordance with an embodiment of theinvention.

FIG. 4B illustrates an example circular buffer representing a secondtime window and a series of counters in accordance with an embodiment ofthe invention.

FIG. 5A illustrates an example linear buffer representing a third timewindow comprising exponentially-decaying time intervals and a series ofassociated counters in accordance with an embodiment of the invention.

FIG. 5B illustrates an example linear buffer representing a fourth timewindow comprising exponentially-decaying time intervals and a series ofassociated counters in accordance with an embodiment of the invention.

FIG. 6 illustrates an example of a computer system that may be used toimplement one or more of the embodiments described herein in accordancewith an embodiment of the invention.

The figures depict various embodiments of the present invention forpurposes of illustration only, wherein the figures use like referencenumerals to identify like elements. One skilled in the art will readilyrecognize from the following discussion that alternative embodiments ofthe structures and methods illustrated in the figures may be employedwithout departing from the principles of the invention described herein.

DETAILED DESCRIPTION Social Networking System—General Introduction

FIG. 1 is a network diagram of a system 100 for tracking events andclassifying assets within a social network in accordance with anembodiment of the invention. The system 100 includes one or more userdevices 110, one or more external systems 120, the social networkingsystem 130, and a network 150. For purposes of illustration, theembodiment of the system 100, shown by FIG. 1, includes a singleexternal system 120 and a single user device 110. However, in otherembodiments, the system 100 may include more user devices 110 and/ormore external systems 120. In certain embodiments, the social networkingsystem 130 is operated by a social network provider, whereas theexternal systems 120 are separate from the social networking system 130in that they may be operated by different entities. In variousembodiments, however, the social networking system 130 and the externalsystems 120 operate in conjunction to provide social networking servicesto users (or members) of the social networking system 130. In thissense, the social networking system 130 provides a platform or backbone,which other systems, such as external systems 120, may use to providesocial networking services and functionalities to users across theInternet.

The user device 110 comprises one or more computing devices that canreceive input from a user and transmit and receive data via the network150. In one embodiment, the user device 110 is a conventional computersystem executing, for example, a Microsoft Windows compatible operatingsystem (OS), Apple OS X, and/or a Linux distribution. In anotherembodiment, the user device 110 can be a device having computerfunctionality, such as a smart-phone, a tablet, a personal digitalassistant (PDA), a mobile telephone, etc. The user device 110 isconfigured to communicate via the network 150. The user device 110 canexecute an application, for example, a browser application that allows auser of the user device 110 to interact with the social networkingsystem 130. In another embodiment, the user device 110 interacts withthe social networking system 130 through an application programminginterface (API) provided by the native operating system of the userdevice 110, such as iOS and ANDROID. The user device 110 is configuredto communicate with the external system 120 and the social networkingsystem 130 via the network 150, which may comprise any combination oflocal area and/or wide area networks, using wired and/or wirelesscommunication systems.

In one embodiment, the network 150 uses standard communicationstechnologies and protocols. Thus, the network 150 can include linksusing technologies such as Ethernet, 802.11, worldwide interoperabilityfor microwave access (WiMAX), 3G, 4G, CDMA, GSM, LTE, digital subscriberline (DSL), etc. Similarly, the networking protocols used on the network150 can include multiprotocol label switching (MPLS), transmissioncontrol protocol/Internet protocol (TCP/IP), User Datagram Protocol(UDP), hypertext transport protocol (HTTP), simple mail transferprotocol (SMTP), file transfer protocol (FTP), and the like. The dataexchanged over the network 150 can be represented using technologiesand/or formats including hypertext markup language (HTML) and extensiblemarkup language (XML). In addition, all or some links can be encryptedusing conventional encryption technologies such as secure sockets layer(SSL), transport layer security (TLS), and Internet Protocol security(IPsec).

In one embodiment, the user device 110 may display content from theexternal system 120 and/or from the social networking system 130 byprocessing a markup language document 114 received from the externalsystem 120 and from the social networking system 130 using a browserapplication 112. The markup language document 114 identifies content andone or more instructions describing formatting or presentation of thecontent. By executing the instructions included in the markup languagedocument 114, the browser application 112 displays the identifiedcontent using the format or presentation described by the markuplanguage document 114. For example, the markup language document 114includes instructions for generating and displaying a web page havingmultiple frames that include text and/or image data retrieved from theexternal system 120 and the social networking system 130. In variousembodiments, the markup language document 114 comprises a data fileincluding extensible markup language (XML) data, extensible hypertextmarkup language (XHTML) data, or other markup language data.Additionally, the markup language document 114 may include JavaScriptObject Notation (JSON) data, JSON with padding (JSONP), and JavaScriptdata to facilitate data-interchange between the external system 120 andthe user device 110. The browser application 112 on the user device 110may use a JavaScript compiler to decode the markup language document114.

The markup language document 114 may also include, or link to,applications or application frameworks such as FLASH™ or Unity™applications, the SilverLight™ application framework, etc.

In one embodiment, the user device 110 also includes one or more cookies116 including data indicating whether a user of the user device 110 islogged into the social networking system 130, which may enablemodification of the data communicated from the social networking system130 to the user device 110.

The external system 120 includes one or more web servers that includeone or more web pages 122 a, 122 b, which are communicated to the userdevice 110 using the network 150. The external system 120 is separatefrom the social networking system 130. For example, the external system120 is associated with a first domain, while the social networkingsystem 130 is associated with a separate social networking domain. Webpages 122 a, 122 b, included in the external system 120, comprise markuplanguage documents 114 identifying content and including instructionsspecifying formatting or presentation of the identified content.

The social networking system 130 includes one or more computing devicesfor a social network, including a plurality of users, and providingusers of the social network with the ability to communicate and interactwith other users of the social network. In some instances, the socialnetwork can be represented by a graph, i.e., a data structure includingedges and nodes. Other data structures can also be used to represent thesocial network, including but not limited to databases, objects,classes, meta elements, files, or any other data structure. The socialnetworking system 130 may be administered, managed, or controlled by anoperator. The operator of the social networking system 130 may be ahuman being, an automated application, or a series of applications formanaging content, regulating policies, and collecting usage metricswithin the social networking system 130 or combination thereof. Any typeof operator may be used.

Users may join the social networking system 130 and then add connectionsto any number of other users of the social networking system 130 to whomthey desire to be connected. As used herein, the term “friend” refers toany other user of the social networking system 130 to whom a user hasformed a connection, association, or relationship via the socialnetworking system 130. For example, in an embodiment, if users in thesocial networking system 130 are represented as nodes in the socialgraph, the term “friend” can refer to an edge formed between anddirectly connecting two user nodes.

Connections may be added explicitly by a user or may be automaticallycreated by the social networking system 130 based on commoncharacteristics of the users (e.g., users who are alumni of the sameeducational institution). For example, a first user specifically selectsa particular other user to be a friend. Connections in the socialnetworking system 130 are usually in both directions, but need not be,so the terms “user” and “friend” depend on the frame of reference.Connections between users of the social networking system 130 areusually bilateral (“two-way”), or “mutual,” but connections may also beunilateral, or “one-way.” For example, if Bob and Joe are both users ofthe social networking system 130 and connected to each other, Bob andJoe are each other's connections. If, on the other hand, Bob wishes toconnect to Joe to view data communicated to the social networking system130 by Joe, but Joe does not wish to form a mutual connection, aunilateral connection may be established. The connection between usersmay be a direct connection; however, some embodiments of the socialnetworking system 130 allow the connection to be indirect via one ormore levels of connections or degrees of separation.

In addition to establishing and maintaining connections between usersand allowing interactions between users, the social networking system130 provides users with the ability to take actions on various types ofitems supported by the social networking system 130. These items mayinclude groups or networks (i.e., social networks of people, entities,and concepts) to which users of the social networking system 130 maybelong, events or calendar entries in which a user might be interested,computer-based applications that a user may use via the socialnetworking system 130, transactions that allow users to buy or sellitems via services provided by or through the social networking system130, and interactions with advertisements that a user may perform on oroff the social networking system 130. These are just a few examples ofthe items upon which a user may act on the social networking system 130,and many others are possible. A user may interact with anything that iscapable of being represented in the social networking system 130 or inthe external system 120, separate from the social networking system 130,or coupled to the social networking system 130 via the network 150.

The social networking system 130 is also capable of linking a variety ofentities. For example, the social networking system 130 enables users tointeract with each other as well as external systems 120 or otherentities through an API, a web service, or other communication channels.The social networking system 130 generates and maintains the “socialgraph” comprising a plurality of nodes interconnected by a plurality ofedges. Each node in the social graph may represent an entity that canact on another node and/or that can be acted on by another node. Thesocial graph may include various types of nodes. Examples of types ofnodes include users, non-person entities, content items, web pages,groups, activities, messages, concepts, and any other things that can berepresented by an object in the social networking system 130. An edgebetween two nodes in the social graph may represent a particular kind ofconnection, or association, between the two nodes, which may result fromnode relationships or from an action that was performed by one of thenodes on the other node. In some cases, the edges between nodes can beweighted. The weight of an edge can represent an attribute associatedwith the edge, such as a strength of the connection or associationbetween nodes. Different types of edges can be provided with differentweights. For example, an edge created when one user “likes” another usermay be given one weight, while an edge created when a user befriendsanother user may be given a different weight.

As an example, when a first user identifies a second user as a friend,an edge in the social graph is generated connecting a node representingthe first user and a second node representing the second user. Asvarious nodes relate or interact with each other, the social networkingsystem 130 modifies edges connecting the various nodes to reflect therelationships and interactions.

The social networking system 130 also includes user-generated content,which enhances a user's interactions with the social networking system130. User-generated content may include anything a user can add, upload,send, or “post” to the social networking system 130. For example, a usercommunicates posts to the social networking system 130 from a userdevice 110. Posts may include data such as status updates or othertextual data, location information, images such as photos, videos,links, music or other similar data and/or media. Content may also beadded to the social networking system 130 by a third-party. Content“items” are represented as objects in the social networking system 130.In this way, users of the social networking system 130 are encouraged tocommunicate with each other by posting text and content items of varioustypes of media through various communication channels. Suchcommunication increases the interaction of users with each other andincreases the frequency with which users interact with the socialnetworking system 130.

The social networking system 130 includes a web server 132, an APIrequest server 134, a user profile store 136, a connection store 138, anaction logger 140, an activity log 142, an authorization server 144, anevent tracking module 146, and an asset classification module 148. In anembodiment of the invention, the social networking system 130 mayinclude additional, fewer, or different components for variousapplications. Other components, such as network interfaces, securitymechanisms, load balancers, failover servers, management and networkoperations consoles, and the like are not shown so as to not obscure thedetails of the system.

The user account store 136 maintains information about user accounts,including biographic, demographic, and other types of descriptiveinformation, such as work experience, educational history, hobbies orpreferences, location, and the like that has been declared by users orinferred by the social networking system 130. This information is storedin the user account store 136 such that each user is uniquelyidentified. The social networking system 130 also stores data describingone or more connections between different users in the connection store138. The connection information may indicate users who have similar orcommon work experience, group memberships, hobbies, or educationalhistory. Additionally, the social networking system 130 includesuser-defined connections between different users, allowing users tospecify their relationships with other users. For example, user-definedconnections allow users to generate relationships with other users thatparallel the users' real-life relationships, such as friends,co-workers, partners, and so forth. Users may select from predefinedtypes of connections, or define their own connection types as needed.Connections with other nodes in the social networking system 130, suchas non-person entities, buckets, cluster centers, images, interests,pages, external systems, concepts, and the like are also stored in theconnection store 138.

The social networking system 130 maintains data about objects with whicha user may interact. To maintain this data, the user account store 136and the connection store 138 store instances of the corresponding typeof objects maintained by the social networking system 130. Each objecttype has information fields that are suitable for storing informationappropriate to the type of object. For example, the user account store136 contains data structures with fields suitable for describing auser's account and information related to a user's account. When a newobject of a particular type is created, the social networking system 130initializes a new data structure of the corresponding type, assigns aunique object identifier to it, and begins to add data to the object asneeded. This might occur, for example, when a user becomes a user of thesocial networking system 130, the social networking system 130 generatesa new instance of a user profile in the user account store 136, assignsa unique identifier to the user account, and begins to populate thefields of the user account with information provided by the user.

The connection store 138 includes data structures suitable fordescribing a user's connections to other users, connections to externalsystems 120 or connections to other entities. The connection store 138may also associate a connection type with a user's connections, whichmay be used in conjunction with the user's privacy setting to regulateaccess to information about the user. In an embodiment of the invention,the user account store 136 and the connection store 138 may beimplemented as a federated database.

Data stored in the connection store 138, the user account store 136, andthe activity log 142 enables the social networking system 130 togenerate the social graph that uses nodes to identify various objectsand edges connecting nodes to identify relationships between differentobjects. For example, if a first user establishes a connection with asecond user in the social networking system 130, user accounts of thefirst user and the second user from the user account store 136 may actas nodes in the social graph. The connection between the first user andthe second user stored by the connection store 138 is an edge betweenthe nodes associated with the first user and the second user. Continuingthis example, the second user may then send the first user a messagewithin the social networking system 130. The action of sending themessage, which may be stored, is another edge between the two nodes inthe social graph representing the first user and the second user.Additionally, the message itself may be identified and included in thesocial graph as another node connected to the nodes representing thefirst user and the second user.

In another example, a first user may tag a second user in an image thatis maintained by the social networking system 130 (or, alternatively, inan image maintained by another system outside of the social networkingsystem 130). The image may itself be represented as a node in the socialnetworking system 130. This tagging action may create edges between thefirst user and the second user as well as create an edge between each ofthe users and the image, which is also a node in the social graph. Inyet another example, if a user confirms attending an event, the user andthe event are nodes obtained from the user account store 136, where theattendance of the event is an edge between the nodes that may beretrieved from the activity log 142. By generating and maintaining thesocial graph, the social networking system 130 includes data describingmany different types of objects and the interactions and connectionsamong those objects, providing a rich source of socially relevantinformation.

The web server 132 links the social networking system 130 to one or moreuser devices 110 and/or one or more external systems 120 via the network150. The web server 132 serves web pages, as well as other web-relatedcontent, such as Java, JavaScript, Flash, XML, and so forth. The webserver 132 may include a mail server or other messaging functionalityfor receiving and routing messages between the social networking system130 and one or more user devices 110. The messages can be instantmessages, queued messages (e.g., email), text and SMS messages, or anyother suitable messaging format.

The API request server 134 allows one or more external systems 120 anduser devices 110 to call access information from the social networkingsystem 130 by calling one or more API functions. The API request server134 may also allow external systems 120 to send information to thesocial networking system 130 by calling APIs. The external system 120,in one embodiment, sends an API request to the social networking system130 via the network 150, and the API request server 134 receives the APIrequest. The API request server 134 processes the request by calling anAPI associated with the API request to generate an appropriate response,which the API request server 134 communicates to the external system 120via the network 150. For example, responsive to an API request, the APIrequest server 134 collects data associated with a user, such as theuser's connections that have logged into the external system 120, andcommunicates the collected data to the external system 120. In anotherembodiment, the user device 110 communicates with the social networkingsystem 130 via APIs in the same manner as external systems 120.

The action logger 140 is capable of receiving communications from theweb server 132 about user actions on and/or off the social networkingsystem 130. The action logger 140 populates the activity log 142 withinformation about user actions, enabling the social networking system130 to discover various actions taken by its users within the socialnetworking system 130 and outside of the social networking system 130.Any action that a particular user takes with respect to another node onthe social networking system 130 may be associated with each user'saccount, through information maintained in the activity log 142 or in asimilar database or other data repository. Examples of actions taken bya user within the social networking system 130 that are identified andstored may include, for example, adding a connection to another user,sending a message to another user, reading a message from another user,viewing content associated with another user, attending an event postedby another user, posting an image, attempting to post an image, or otheractions interacting with another user or another object. When a usertakes an action within the social networking system 130, the action isrecorded in the activity log 142. In one embodiment, the socialnetworking system 130 maintains the activity log 142 as a database ofentries. When an action is taken within the social networking system130, an entry for the action is added to the activity log 142. Theactivity log 142 may be referred to as an action log.

Additionally, user actions may be associated with concepts and actionsthat occur within an entity outside of the social networking system 130,such as an external system 120 that is separate from the socialnetworking system 130. For example, the action logger 140 may receivedata describing a user's interaction with an external system 120 fromthe web server 132. In this example, the external system 120 reports auser's interaction according to structured actions and objects in thesocial graph.

Other examples of actions where a user interacts with an external system120 include a user expressing an interest in an external system 120 oranother entity, a user posting a comment to the social networking system130 that discusses an external system 120 or a web page 122 a within theexternal system 120, a user posting to the social networking system 130a Uniform Resource Locator (URL) or other identifier associated with anexternal system 120, a user attending an event associated with anexternal system 120, or any other action by a user that is related to anexternal system 120. Thus, the activity log 142 may include actionsdescribing interactions between a user of the social networking system130 and an external system 120 that is separate from the socialnetworking system 130.

The authorization server 144 enforces one or more privacy settings ofthe users of the social networking system 130. A privacy setting of auser determines how particular information associated with a user can beshared. The privacy setting comprises the specification of particularinformation associated with a user and the specification of the entityor entities with whom the information can be shared. Examples ofentities with which information can be shared may include other users,applications, external systems 120, or any entity that can potentiallyaccess the information. The information that can be shared by a usercomprises user account information, such as profile photos, phonenumbers associated with the user, user's connections, actions taken bythe user such as adding a connection, changing user profile information,and the like.

The privacy setting specification may be provided at different levels ofgranularity. For example, the privacy setting may identify specificinformation to be shared with other users; the privacy settingidentifies a work phone number or a specific set of related information,such as, personal information including profile photo, home phonenumber, and status. Alternatively, the privacy setting may apply to allthe information associated with the user. The specification of the setof entities that can access particular information can also be specifiedat various levels of granularity. Various sets of entities with whichinformation can be shared may include, for example, all friends of theuser, all friends of friends, all applications, or all external systems120. One embodiment allows the specification of the set of entities tocomprise an enumeration of entities. For example, the user may provide alist of external systems 120 that are allowed to access certaininformation. Another embodiment allows the specification to comprise aset of entities along with exceptions that are not allowed to access theinformation. For example, a user may allow all external systems 120 toaccess the user's work information, but specify a list of externalsystems 120 that are not allowed to access the work information. Certainembodiments call the list of exceptions that are not allowed to accesscertain information a “block list”. External systems 120 belonging to ablock list specified by a user are blocked from accessing theinformation specified in the privacy setting. Various combinations ofgranularity of specification of information, and granularity ofspecification of entities, with which information is shared arepossible. For example, all personal information may be shared withfriends whereas all work information may be shared with friends offriends.

The authorization server 144 contains logic to determine if certaininformation associated with a user can be accessed by a user's friends,external systems 120, and/or other applications and entities. Theexternal system 120 may need authorization from the authorization server144 to access the user's more private and sensitive information, such asthe user's work phone number. Based on the user's privacy settings, theauthorization server 144 determines if another user, the external system120, an application, or another entity is allowed to access informationassociated with the user, including information about actions taken bythe user.

The social networking system 130 may include a event tracking module 146and an asset classification module 148. The event tracking module 146may detect the occurrence of events involving assets within the socialnetworking system 130 based on time windows and counters, as describedfurther below. The asset classification module 148 may classify theassets based on decision trees, machine learning modules, or othertechniques. The techniques may be performed based on the events trackedby the event tracking module 146.

Tracking Events Using Time-Windowed Counters

Various events may occur within the social networking system 130. Anevent may refer to a user interaction with a content item, a userinteraction with another user, creation of a message, or any actioninvolving an asset within the social networking system 130. An asset mayrefer to any data item created by, communicated within, or otherwiserelated to the social networking system 130 that may be of interest tothe operator of the social networking system 130. For example, an assetmay be a user, a content item, an IP address, a URL, a message, or anyother item handled by the social networking system 130. The operator ofthe social networking system 130 may wish to track all of the variousevents that have occurred involving a particular asset. For example, theoperator of the social networking system 130 may wish to determine howmany unique users have interacted with a particular asset. By gatheringspecific information on assets and events, the operator of the socialnetworking system 130 may be able to make informed design decisionsabout the functionality, user interface, policies, and other dimensionsof the social networking system 130.

The operator of the social networking system 130 may wish to trackevents within specific time periods. Determining the number of eventsthat occur within particular time periods may allow the operator toidentify trends, spikes, and other variations in activity involvingassets. In addition, creating further delineations within the timeperiod may allow the operator to determine how activity trends involvinga user or an asset changed over the course of the time period. Forexample, the social networking system 130 may determine that a userlogged into his account on the social networking system 130 30 timesover the previous week. This information may be useful, but it may bemore beneficial to learn that the user logged into his account threetimes on Monday, four times on Tuesday, four times on Wednesday, 15times on Thursday, once on Friday, two times on Saturday, and once onSunday. The social networking system 130 may identify a spike in thenumber of times the user logged in on Thursday, which may allow thesocial networking system 130 to, for example, optimize aspects of theuser's experience or take other appropriate action.

According to an embodiment, the data gathered using event trackingtechniques may be used for asset classification. If the socialnetworking system 130 has numerous users, the social networking system130 may classify assets based on the events involving the assets. Byclassifying assets, the social networking system 130 may make decisionsand take appropriate action based on such classifications. For example,the social networking system 130 may determine which content items toinclude in a content feed of a user based on the classification of theuser. As another example, the social networking system 130 may determinewhich content items to block or filter in a content feed or otherfunctionality of the social networking system 130.

One application in which asset classification may be useful is spamdetection. As user adoption of social networks has grown, socialnetworks have become an increasingly popular platform for entities todeliver spam, e.g., unsolicited messages or content. Spam content itemsmay be disguised as legitimate content items in order to mislead usersinto interacting with them. In addition, a spam content item may includehidden functionality that allows the content item to replicate itselfwhen the user has interacted with it. For example, a URL leading to aspam site may be disguised as a link to a site with a legitimatepurpose. A user may click on the link, which may activate functionalitythat posts the link to the profiles of all of the user's friends in thesocial networking system 130. Spam may diminish the quality of the userexperience of the social networking system 130. A user may hesitate tointeract with a content item if he is unsure that it genuinely serves alegitimate purpose. If spammers are able to spread content itemsthroughout the social networking system 130, the utility of contentsharing functionality of the social networking system 130, such as thenews feed, may be negatively affected. To address this concern, thesocial networking system 130 may classify certain assets as spam basedon their event history. The social networking system 130 may then takeaction against assets based on their classification. For example, theaccounts of users that are classified as spammers may be blocked,terminated, or flagged for further review. As another example, whenusers attempt to interact with content items that are classified asspam, the social networking system 130 may prompt them with warnings orrequests for verification.

Embodiments of the invention provide a technique for tracking events andclassifying assets within the social networking system 130 based oncounters and time windows. A counter may refer to a variable used tokeep track of the occurrence of a type of event (or event) within thesocial networking system 130. The counter may be incremented each time atype of event (or event) occurs. Each type of event may have one or moreunique counters associated with it. The social networking system 130 maycreate counters for the types of events that are to be tracked overvarious windows of time. A time window may refer to a period of time.The time window may be defined with reference to any length of time,e.g., the previous week, or with respect to any specified beginningpoint and end point, e.g., between 12:00 PM on July 24 and 5:00 AM onAugust 1. The time window may refer to any time period in the past,e.g., the previous three days, or any time period in the future, e.g.,the next three days. The techniques provided by the embodiments of thepresent invention may be performed in real-time or asynchronously (e.g.,in a periodic batch).

According to an embodiment of the invention, a time window may befurther divided into time intervals. A time interval, or bucket, mayrefer to a discrete time period smaller than the time period encompassedby the time window. A sum of time intervals may be equivalent to thetime period encompassed by the time window. For example, a time windowof one hour may be divided into ten time intervals of six minutes each.In an embodiment, each time interval may have a counter associated withit, such that the counter tracks the number of times a type of event hasoccurred within the time interval. With respect to tracking events andasset classification within the social networking system 130, the numberof time intervals within a time window may be adjusted based on thedegree of precision desired and the amount of storage available. A largenumber of time intervals may result in the creation of a relativelygreater number of counters and may facilitate a higher degree ofprecision, but would require more storage. A smaller number of timeintervals may result in the creation of a relatively fewer number ofcounters and may save storage, but result in a lower degree ofprecision.

According to an embodiment of the invention, a time series for aparticular event or type of event involving a particular asset may bederived using counters and time windows. The time series of an eventtype may represent the number of times the event type is occurring at agiven moment. The time series of the event type may be expressed as afunction and a curve on a graph. The number of times an event type hasoccurred in a specific period of time may be referred to as a signal.The value of a signal may be determined by solving one or morefunctions. In an embodiment, the function for determining the value of asignal may comprise an integral for computing the area under the curverepresenting the signal.

According to an embodiment of the invention, an asset may be classifiedbased on the values of signals. The social networking system 130 may useprocedures for classifying assets. The procedures for classifying assetsmay use decision trees, machine learning models, and other techniquesfor processing and interpreting the signal values. The procedures may bebased on the values of multiple signals related to the same asset. In anembodiment, the procedures may be based on a signal value that reflectsthe total number of events of a first type involving a particular assetas well as a signal value that reflects the total number of events of asecond type involving the particular asset. In an embodiment, theprocedures may be based on a signal value that reflects the total numberof events involving a particular asset as well as a signal value thatreflects the number of events involving the particular asset and uniqueusers.

The social networking system 130 may track events involving uniqueness,such as unique users in addition to tracking total events. Informationabout events involving uniqueness may offer additional perspective onthe activity involving an asset. The additional perspective, in turn,may allow the social networking system 130 to better classify an assetor otherwise take appropriate action.

For example, the social networking system 130 may use counters to trackhow many times a URL http://www.xyz.com has been shared within thesocial networking system 130. The social networking system 130 mayinitialize a first counter that is incremented each time the URLhttp://www.xyz.com is shared within the social networking system 130.The social networking system 130 may initialize a second counter that isincremented each time the URL http://www.xyz.com is shared within thesocial networking system 130 by a unique user. In one embodiment, thesecond counter may be incremented only when the URL http://www.xyz.comis shared by a user who has not previously shared it. The socialnetworking system 130 may derive a function and an accompanying graphillustrating a time series of the number of times the URLhttp://www.xyz.com has been shared within the social networking system130.

FIGS. 2A-B are illustrations of an example graph 200 including a timeseries of the number of times the URL http://www.xyz.com has been sharedwithin the social networking system 130 in accordance with an embodimentof the invention. In the graph 200, the x-axis represents time and they-axis represents the number of times the URL http://www.xyz.com isbeing shared within the social networking system 130 at a given time.Curve 201 represents the number of times the URL http://www.xyz.com hasbeen shared within the social networking system 130 over time. Curve 202represents the number of times the URL http://www.xyz.com has beenshared within the social networking system 130 by unique users overtime. The graph 200 encompasses the time period from 9:00 AM until 3:00PM, which may represent the current time, a previous time, or aprospective time.

The social networking system 130 may determine signal values such as thetotal number of times f₁ the URL http://www.xyz.com has been sharedwithin the social networking system 130 in the previous hour and thetotal number of times f₂ the URL http://www.xyz.com has been sharedwithin the social networking system 130 in the previous three hours,which may be expressed as

-   -   f₁=SigVal_(t)(n(y), 1 hr) and    -   f₂=SigVal_(t)(n(y), 3 hr), respectively, where n(y) represents        the function of the curve 201. In an embodiment, SigVal_(t) may        comprise an integral over time. The total number of times f₁ the        URL http://www.xyz.com has been shared within the social        networking system 130 in the previous hour and the total number        of times f₂ the URL http://www.xyz.com has been shared within        the social networking system 130 in the previous three hours are        represented by shaded regions 203 and 204, respectively, on the        graph 200.

The social networking system 130 also may determine additional signalvalues, such as the number of times g₁ the URL http://www.xyz.com hasbeen shared within the social networking system 130 by unique users inthe previous one hour and the number of times g₂ the URLhttp://www.xyz.com has been shared within the social networking system130 by unique users in the previous three hours, which may be expressedas:

-   -   g₁=SigVal_(u)(p(y), 1 hr) and    -   g₂=SigVal_(u)(p(y), 3 hr),        respectively, where p(y) represents the function of the curve        202. In an embodiment, SigVal_(u) may comprise an integral over        time. The number of times the URL http://www.xyz.com has been        shared within the social networking system 130 by unique users        in the previous hour g₁ and the number of times the URL        http://www.xyz.com has been shared within the social networking        system 130 by unique users in the previous three hours g₂ are        represented by shaded regions 205 and 206, respectively, on the        graph 200.

The signal values f_(t), f₂, g₁ and g₂ may be used in a procedure forclassifying the URL http://www.xyz.com. The procedure may be based ondecision trees, machine learning models, and other techniques forprocessing and interpreting the signal values. In an embodiment, theprocedure may generate a score that correlates to a particularclassification. For example, the classification may relate to whether ornot the URL http://www.xyz.com is spam, the popularity of the URLhttp://www.xyz.com, the type of site that the URL http://www.xyz.comdirects to, or any other information about the URL http://www.xyz.com orassets associated with the URL http://www.xyz.com. If the URLhttp://www.xyz.com is classified as spam, the social networking system130 may, for example, display a warning to users who click on it. If theURL http://www.xyz.com is classified as spam, the social networkingsystem 130 may, for example, require users who attempt to share it tocomplete a verification test to confirm that the user is not a spammeror that the user has not been misled by a spammer to share the link. Inan embodiment, the social networking system 130 may consider portions ofURLs as distinct assets and track events involving each portion. Forexample, the social networking system 130 may track sharing of all URLsthat include the domain xyz.com.

The social networking system 130 may track sharing of the URLhttp://www.xyz.com by unique users because information about sharing byunique users may be more informative than information about sharing byall users. For example, if the social networking system 130 determinesonly that the URL http://www.xyz.com has been shared by 100 users in thepast hour, then the social networking system 130 may conclude that theURL is popular. However, if the social networking system 130 determinesthat the URL http://www.xyz.com has been shared 100 times by a singleuser in the past hour, then the social networking system 130 mayconclude that the URL is spam. Other applications that track uniquenessin events within the social networking system 130 may be employed forclassification purposes.

According to an embodiment of the invention, the social networkingsystem 130 may track multiple types of events involving an asset. Asignal value reflecting each type of event may be used in a procedurefor classifying the asset. For example, the URL http://www.xyz.com maybe clicked or hidden (e.g., when a user selects an option to remove theURL from his news feed) in addition to being shared. The socialnetworking system may track the total number of times that the URLhttp://www.xyz.com was clicked, the total number of times the URLhttp://www.xyz.com was shared, and the total number of times that theURL http://www.xyz.com was hidden. The URL http://www.xyz.com may beclassified based on a procedure that uses signal values reflecting thetotal number of times that the URL http://www.xyz.com has been clicked,shared, and hidden.

According to an embodiment of the invention, signal values reflectingevents that occurred over different time series may be used in aprocedure. For example, the social networking system 130 may track thenumber of times that the URL http://www.xyz.com was clicked, shared, andhidden over the previous five minutes, the previous hour, and theprevious day. This may result in nine signal values, based on threedifferent time series. Each of the nine signal values may be used by aprocedure to classify the URL http://www.xyz.com.

FIG. 3 illustrates a process 300 for classifying an asset in accordancewith an embodiment of the invention. At block 301, the social networkingsystem 130 determines at least one time window. At block 302, the socialnetworking system 130 initializes at least one counter that tracks thenumber of occurrences of a particular event type involving the asset. Inan embodiment, the counter may be associated with the time window. Thecounter may be incremented every time an event of the event type occurswithin the time window. At block 303, the social networking system 130generates a time series based on a signal and the value of the counterand the time window. At block 304, the social networking system 130determines at least one signal value for the signal associated with atime period. In an embodiment, the signal value may be determined bycalculating the area corresponding to the time period under the portionof a curve representing the signal in the time series. The area underthe curve may be determined based on an integration. At block 305, thesocial networking system 130 executes a classification procedure usingthe signal value. The classification procedure may incorporate decisiontrees, machine learning models, and other techniques for processing andinterpreting signal values. At block 306, the social networking system130 classifies the asset based on a result generated by theclassification procedure. The asset may be classified based on whetheror not it relates to spam, popularity, ranking, or any other category orcriterion relevant to the operation and function of the socialnetworking system 130. Popularity may refer to the frequency with whichevents involving an asset occur. For example, the popularity of a usermay be determined based on the number of messages received by the user.Ranking may refer to the position of an asset relative to other assetsbased on a criterion. For example, various URLs may be ranked based onthe frequency with which they are shared. In an embodiment, the process300 may be performed in whole or in part by the event tracking module146, the asset classification module 148, or any other module of thesocial networking system 130.

According to an embodiment of the invention, the time windows and timeintervals may be implemented as data structures comprising elements. Anelement is a discrete component of a data structure with which a valuemay be associated. Each data structure may represent a time window, andan element of a data structure may represent a time interval within thetime window. Each counter may be implemented as a variable associatedwith an element. Thus, each variable may track the occurrence of eventswithin the time interval represented by the element with which thevariable is associated. The data structures, elements, and variables maybe stored within a memory caching system of the social networking system130.

According to an embodiment of the invention, the counters and timewindows may be implemented as circular buffers. A circular buffer is adata structure with discrete elements to which new data may be added byoverwriting elements containing older data. In a circular buffer, theelements may be overwritten according to the order in which data wasadded to them; e.g., when new data needs to be added to the buffer, itis stored in the element containing the oldest data, thereby overwritingthat oldest data. In an embodiment, a circular buffer may represent atime window, and the elements within the circular buffer may representtime intervals within the time window. The time intervals may be ofequal or non-equal length, wherein the sum of the time intervals isequal to the period of time encompassed by the time window. For example,a circular buffer representing a time window of one minute may comprisesix elements representing time intervals of ten seconds each. As timeelapses and events occur, the social networking system 130 may incrementa counter stored within the element representing the current timeinterval. When the current time interval ends, the social networkingsystem 130 may reset a counter within the element representing the leastrecent time interval and re-assign the element to the new current timeinterval. In an embodiment, the social networking system 130 may trackevents over multiple time windows of any varying durations and maintainseparate circular buffers for each time window. In an embodiment, datacollected using circular buffers may be analyzed in real-time. In anembodiment, data collected using circular buffers may be analyzed usingprocesses and techniques that are performed asynchronously.

FIGS. 4A and 4B illustrate an example circular buffer 400 representing atime window and a series of counters in accordance with an embodiment ofthe invention. The time window and counters may track the occurrences ofa particular type of event involving a particular asset. The buffer 400comprises eight elements 401, 402, 403, 404, 405, 406, 407, and 408. Thebuffer 400 represents a continuous one hour and twenty minute timewindow. Each of the elements represents a ten-minute time intervalwithin the time window. In FIG. 4A, the current time is 12:45 and acounter has been incremented during the current time interval 23 times.The element 401 represents the time interval beginning at 11:30. Duringthe time interval beginning at 11:30, a counter was incremented fivetimes. In FIG. 4B, ten minutes have elapsed, and the current time is12:55. Because the element 401 represented the least recent timeinterval in FIG. 4A, i.e, the time interval beginning at 11:30, the datain the element 401 has been overwritten in FIG. 4B with a new counterassociated with the current time interval. Thus, the element 401 in FIG.4B has been re-assigned to the current time interval. The new counterassociated with the current time interval in FIG. 4B has beenincremented twice, indicating that two events have occurred between12:50 and 12:55.

According to an embodiment of the invention, the counters and timewindows may be implemented as linear buffers. In an embodiment, a linearbuffer may be used to implement a time window with exponentiallydecaying time intervals. Exponentially decaying time intervals may referto time intervals that are not of uniform duration and may become largeras time elapses. In one embodiment, time intervals may vary in durationaccording to any desired relationship, such as mathematically linear orexponential functions. For example, the duration of each time intervalmay be twice that of the time interval it precedes. In this regard, themost recent time interval may be one minute long, the next time intervalmay be two minutes long, the next time interval may be four minuteslong, the next time interval may be eight minutes long, etc. Thus, theduration of the time intervals may change as time elapses.

In a time window comprising exponentially decaying time intervals, ifeach time interval has an associated counter, each counter may need tobe continuously or periodically updated to accurately reflect the timeinterval within which each event occurred as time elapses. In anembodiment, the least recent time interval may be a fixed or expandingtime interval whose counter is incremented or decremented as timeelapses to account for the occurrence of events that were previouslyassociated with later time intervals. The number of time intervals to becreated and their duration may be pre-determined. Exponentially decayingtime intervals may allow precise tracking of recent events whileconserving storage capacity by passing a record of the occurrence ofevents to progressively larger time intervals as time progresses and theevents become less recent. In an embodiment, the linear buffer may havea storage limit associated with the maximum length of time for the timewindow. In an embodiment, the maximum length of time may be one year. Inother embodiments, the maximum length of time may be any duration, suchas a day, a week, a month, etc. In an embodiment, data collected usinglinear buffers and exponentially decaying time intervals may be analyzedin real-time. In an embodiment, data collected using linear buffers andexponentially decaying time intervals may be analyzed using processesand techniques that are performed asynchronously.

FIGS. 5A and 5B illustrate an example linear buffer 500 representing atime window comprising exponentially-decaying time intervals and aseries of associated counters in accordance with an embodiment of theinvention. The time window and counters may track the occurrence of aparticular type of event involving a particular asset. In FIG. 5A,element 501 represents the most recent 1-minute time interval beginningat 12:44 and ending at 12:45, element 502 represents a previous 2-minutetime interval beginning at 12:42 and ending at 12:44, element 503represents a previous 4-minute time interval beginning at 12:38 andending at 12:42, and element 504 represents a previous 8-minute timeinterval beginning at 12:30 and ending at 12:38. Each element stores acounter associated with the time interval representing the element. At12:30, the time window was created and the linear buffer wasinitialized. In FIG. 5A, approximately 15 minutes have elapsed betweenthe creation of the time window and the current time, 12:44:23. Acounter associated with the element 501 has been incremented 7 times,indicating that 7 events have occurred in the time interval representedby the element 501. A counter associated with the element 502 has beenincremented 34 times, indicating that 34 events have occurred in thetime interval represented by the element 502. A counter associated withthe element 503 has been incremented 50 times, indicating that 50 eventshave occurred in the time interval representing the element 503. Acounter associated with the element 504 has been incremented 72 times,indicating that 72 events have occurred in the time intervalrepresenting the element 504.

In FIG. 5B, approximately 2 minutes have elapsed and the current time is12:46:30. Each of the time windows have been shifted forward by 2minutes, such that the element 501 represents the most recent 1-minutetime interval beginning at 12:46 and ending at 12:47, the element 502represents a previous 2-minute time interval beginning at 12:44 andending at 12:46, the element 503 represents a previous 4-minute timeinterval beginning at 12:40 and ending at 12:44, and the element 504represents a previous 10-minute time interval beginning at 12:30 andending at 12:40. Thus, in the illustrated example, the element 504represents an expanding time interval. As indicated by arrow 505, theseven events that occurred within the time interval between 12:44 and12:45 are passed from the counter associated with the element 501 to thecounter associated with the element 502. As indicated by arrow 506, the34 events that occurred within the time interval between 12:42 and 12:44are passed from the counter associated with the element 502 to thecounter associated with the element 503. The earlier half of the timeinterval between 12:38 and 12:42 falls within the time intervalrepresented by element 503 and the latter half of the time intervalbetween 12:38 and 12:42 falls within the time interval represented bythe element 504. Accordingly, as indicated by arrows 507 and 508, halfof the 50 events that occurred between 12:38 and 12:42 are kept withinthe counter associated with the element 503 and half are passed to thecounter associated with the element 504. As indicated by arrow 509, the72 events that occurred within the time interval between 12:30 and 12:38are kept in the element 504. To reflect one event that has occurred inthe approximately two minutes that have elapsed between 12:44:23 and12:46:30, the counter associated with the element 501 representing thetime window between 12:46 and 12:47 is reset and incremented once. Thus,the counters associated with the elements are updated to have values of1, 7, 59, and 97, respectively.

According to an embodiment of the invention, a linear buffer may be usedto implement a time window comprising non-decreasing time intervals. Anon-decreasing time interval may be a time interval of fixed size. Eachelement in the linear buffer may represent a non-decreasing timeinterval with an associated counter. When the interval commences, itsassociated counter may be incremented every time an event of aparticular type involving a particular asset occurs. When the intervalends, its associated counter may no longer need to be updated oroverwritten, as may be the case with a circular buffer. Time windowswith non-decreasing intervals may have larger storage requirements, butmay also allow for greater precision in tracking less recent events.This may be particularly useful for analyzing comparable time intervalsfor a particular type of event.

For example, there may be a sudden rise in the number of times users ofthe social networking system 130 share a URL of a sports site during aspecific time interval (e.g., from 12:30 PM to 1:30 PM) on the mostrecent Sunday. Absent further information, the social networking system130 may be unable to attribute the rise to any cause. If user sharing ofthe URL is tracked using time windows with non-decreasing timeintervals, the social networking system 130 may compare the rise insharing of the URL during the specific time interval on the most recentSunday with the number of times the URL was shared during an analogoustime interval on previous Sundays (e.g., 12:00 PM on Sunday 9/2 comparedwith 12:00 PM on Sunday 8/26). In an embodiment, the social networkingsystem 130 may analyze trends in the occurrence of a type of event bycomparing a recent time interval to a previous time interval. The socialnetworking system 130 may observe similar rises in user sharing of theURL on previous Sundays and correlate the rise to weekly football gamesthat occur mainly on Sundays during the early afternoon. In anembodiment, data collected using linear buffers and non-decreasing timeintervals may be analyzed in real-time. In an embodiment, data collectedusing linear buffers and non-decreasing time intervals may be analyzedusing processes and techniques that are performed asynchronously.

User sharing of the URL instead may be tracked using circular buffers,exponentially-decaying time buffers, or other types of time intervals.In the case of circular buffers, the number of times the URL was sharedduring a time interval of a previous Sunday may be overwritten if thedistance in time between the time interval of the previous Sunday andthe time interval of the most recent Sunday is larger than the timewindow of the circular buffer. As a result, time-windowed comparisons ofURL sharing occurrences would be difficult or impossible in someinstances. In the case of exponentially-decaying time intervals, thenumber of times the URL was shared during the time interval of theprevious Sunday may have been passed to a counter associated with a muchlonger time interval. A resulting loss of granularity in the ability tocorrelate recent events with events that are passed to increasinglylonger time intervals may preclude meaningful time-windowed comparisonof URL sharing occurrences. The selective use of certain buffers or timeintervals accordingly may pose advantages in allowing time-windowedcomparisons.

According to an embodiment of the invention, the social networkingsystem 130 may use time windows and counters to evaluate or modifypolicies. The social networking system 130 may implement policies thatregulate user interactions with certain types of content. A policy maybe implemented using an asset. For example, if a certain URL issuspected to be spam, the social networking system 130 may require everyfifth user who shares the URL to complete a verification test before theshare is submitted. The social networking system 130 may track how manyusers pass or fail the verification test over time. If a majority of theusers pass the verification test, then the suspicion that the URL isspam may lessen and the social networking system 130 may decrease thenumber of users who are required to complete the verification test. If amajority of the users fail the verification test, then the suspicionthat the URL is spam may heighten and the social networking system 130may increase the number of users who are required to complete theverification test. The social networking system 130 may compare the passrate of the verification test in a recent time window with the pass rateof the verification test in a previous time window. By comparing passrates, the social networking system 130 may, for example, detect ifspammers have developed techniques to circumvent the verification testover time. In an embodiment, a verification test may be an asset. A userpassing the test and a user failing the test may be considered distincttypes of events, and the occurrences of each type of event may betracked by the social networking system 130 using any of the techniquesdescribed herein.

Hardware Implementation

The foregoing processes and features can be implemented by a widevariety of machine and computer system architectures and in a widevariety of network and computing environments. FIG. 6 illustrates anexample of a computer system 600 that may be used to implement one ormore of the embodiments described herein in accordance with anembodiment of the invention. The computer system 600 includes sets ofinstructions for causing the computer system 600 to perform theprocesses and features discussed herein. The computer system 600 may beconnected (e.g., networked) to other machines. In a networkeddeployment, the computer system 600 may operate in the capacity of aserver machine or a client machine in a client-server networkenvironment, or as a peer machine in a peer-to-peer (or distributed)network environment. In an embodiment of the invention, the computersystem 600 may be the social networking system 130, the user device 110,and the external system 120, or a component thereof. In an embodiment ofthe invention, the computer system 600 may be one server among many thatconstitutes all or part of the social networking system 130.

The computer system 600 includes a processor 602, a cache 604, and oneor more executable modules and drivers, stored on a computer-readablemedium, directed to the processes and features described herein.Additionally, the computer system 600 includes a high performanceinput/output (I/O) bus 606 and a standard I/O bus 608. A host bridge 610couples processor 602 to high performance I/O bus 606, whereas I/O busbridge 612 couples the two buses 606 and 608 to each other. A systemmemory 614 and one or more network interfaces 616 couple to highperformance I/O bus 606. The computer system 600 may further includevideo memory and a display device coupled to the video memory (notshown). Mass storage 618 and I/O ports 620 couple to the standard I/Obus 608. The computer system 600 may optionally include a keyboard andpointing device, a display device, or other input/output devices (notshown) coupled to the standard I/O bus 608. Collectively, these elementsare intended to represent a broad category of computer hardware systems,including but not limited to computer systems based on thex86-compatible processors manufactured by Intel Corporation of SantaClara, Calif., and the x86-compatible processors manufactured byAdvanced Micro Devices (AMD), Inc., of Sunnyvale, Calif., as well as anyother suitable processor.

An operating system manages and controls the operation of the computersystem 600, including the input and output of data to and from softwareapplications (not shown). The operating system provides an interfacebetween the software applications being executed on the system and thehardware components of the system. Any suitable operating system may beused, such as the LINUX Operating System, the Apple Macintosh OperatingSystem, available from Apple Computer Inc. of Cupertino, Calif., UNIXoperating systems, Microsoft® Windows® operating systems, BSD operatingsystems, and the like. Other implementations are possible.

The elements of the computer system 600 are described in greater detailbelow. In particular, the network interface 616 provides communicationbetween the computer system 600 and any of a wide range of networks,such as an Ethernet (e.g., IEEE 802.3) network, a backplane, etc. Themass storage 618 provides permanent storage for the data and programminginstructions to perform the above-described processes and featuresimplemented by the respective computing systems identified above,whereas the system memory 614 (e.g., DRAM) provides temporary storagefor the data and programming instructions when executed by the processor602. The I/O ports 620 may be one or more serial and/or parallelcommunication ports that provide communication between additionalperipheral devices, which may be coupled to the computer system 600.

The computer system 600 may include a variety of system architectures,and various components of the computer system 600 may be rearranged. Forexample, the cache 604 may be on-chip with processor 602. Alternatively,the cache 604 and the processor 602 may be packed together as a“processor module”, with processor 602 being referred to as the“processor core”. Furthermore, certain embodiments of the invention mayneither require nor include all of the above components. For example,peripheral devices coupled to the standard I/O bus 608 may couple to thehigh performance I/O bus 606. In addition, in some embodiments, only asingle bus may exist, with the components of the computer system 600being coupled to the single bus. Furthermore, the computer system 600may include additional components, such as additional processors,storage devices, or memories.

In general, the processes and features described herein may beimplemented as part of an operating system or a specific application,component, program, object, module, or series of instructions referredto as “programs”. For example, one or more programs may be used toexecute specific processes described herein. The programs typicallycomprise one or more instructions in various memory and storage devicesin the computer system 600 that, when read and executed by one or moreprocessors, cause the computer system 600 to perform operations toexecute the processes and features described herein. The processes andfeatures described herein may be implemented in software, firmware,hardware (e.g., an application specific integrated circuit), or anycombination thereof.

In one implementation, the processes and features described herein areimplemented as a series of executable modules run by the computer system600, individually or collectively in a distributed computingenvironment. The foregoing modules may be realized by hardware,executable modules stored on a computer-readable medium (ormachine-readable medium), or a combination of both. For example, themodules may comprise a plurality or series of instructions to beexecuted by a processor in a hardware system, such as the processor 602.Initially, the series of instructions may be stored on a storage device,such as the mass storage 618. However, the series of instructions can bestored on any suitable computer readable storage medium. Furthermore,the series of instructions need not be stored locally, and could bereceived from a remote storage device, such as a server on a network,via the network interface 616. The instructions are copied from thestorage device, such as the mass storage 618, into the system memory 614and then accessed and executed by the processor 602.

Examples of computer-readable media include, but are not limited to,recordable type media such as volatile and non-volatile memory devices;solid state memories; floppy and other removable disks; hard diskdrives; magnetic media; optical disks (e.g., Compact Disk Read-OnlyMemory (CD ROMS), Digital Versatile Disks (DVDs)); other similarnon-transitory (or transitory), tangible (or non-tangible) storagemedium; or any type of medium suitable for storing, encoding, orcarrying a series of instructions for execution by the computer system600 to perform any one or more of the processes and features describedherein.

For purposes of explanation, numerous specific details are set forth inorder to provide a thorough understanding of the description. It will beapparent, however, to one skilled in the art that embodiments of thedisclosure can be practiced without these specific details. In someinstances, modules, structures, processes, features, and devices areshown in block diagram form in order to avoid obscuring the description.In other instances, functional block diagrams and flow diagrams areshown to represent data and logic flows. The components of blockdiagrams and flow diagrams (e.g., modules, blocks, structures, devices,features, etc.) may be variously combined, separated, removed,reordered, and replaced in a manner other than as expressly describedand depicted herein.

Reference in this specification to “one embodiment”, “an embodiment”,“other embodiments”, “one series of embodiments”, or the like means thata particular feature, design, structure, or characteristic described inconnection with the embodiment is included in at least one embodiment ofthe disclosure. The appearances of, for example, the phrase “in oneembodiment” or “in an embodiment” in various places in the specificationare not necessarily all referring to the same embodiment, nor areseparate or alternative embodiments mutually exclusive of otherembodiments. Moreover, whether or not there is express reference to an“embodiment” or the like, various features are described, which may bevariously combined and included in some embodiments, but also variouslyomitted in other embodiments. Similarly, various features are describedthat may be preferences or requirements for some embodiments, but notother embodiments.

The language used herein has been principally selected for readabilityand instructional purposes, and it may not have been selected todelineate or circumscribe the inventive subject matter. It is thereforeintended that the scope of the invention be limited not by this detaileddescription, but rather by any claims that issue on an application basedhereon. Accordingly, the disclosure of the embodiments of the inventionis intended to be illustrative, but not limiting, of the scope of theinvention, which is set forth in the following claims.

What is claimed:
 1. A computer-implemented method, comprising:generating, by a computer system, a time series of occurrences of anevent type associated with at least an asset trackable by the computersystem, wherein the time series includes a series of occurrence countersand spans a time window that is divided into time intervals, and theoccurrence counters correspond respectively to the time intervals;computing, by the computer system, a first signal value based on a firstsubset of the time series; computing, by the computer system, a secondsignal value based on a second subset of the time series, wherein thesecond subset is different from the first subset; classifying, by thecomputer system, the asset into a category based on the first signalvalue and the second signal value; and modifying, based on the category,a policy in the computer system for a user or a service of the computersystem to interact with the asset.
 2. The computer-implemented method ofclaim 1, wherein modifying the policy further comprises at least one of:requiring an additional step when a user interacts with the asset,blocking or terminating an interaction involving the asset, or changinga ranking or popularity associated with the asset.
 3. Thecomputer-implemented method of claim 1, wherein generating the timeseries includes updating the time series in real-time as a new instanceof the event type occurs and is recorded by the computer system.
 4. Thecomputer-implemented method of claim 1, wherein classifying the assetincludes comparing the first signal value and the second signal value.5. The computer-implemented method of claim 1, wherein the computersystem is a social networking system and wherein the asset is a dataitem created by, communicated within, or related to the socialnetworking system.
 6. The computer-implemented method of claim 5,wherein the event type is associated with a recordable action involvinga social object in a social graph of the social networking system. 7.The computer-implemented method of claim 5, wherein the event type isassociated with a user interaction involving a user of the socialnetworking system.
 8. The computer-implemented method of claim 1,wherein generating the time series further comprises: storing the timeseries in a circular buffer; and resetting the at least one of theoccurrence counters at an edge of the circular buffer.
 9. Thecomputer-implemented method of claim 1, wherein generating the timeseries includes incrementing at least one of the occurrence counterswhen an instance of the event type involving the asset occurs within atime interval corresponding to the at least one occurrence counter. 10.The computer-implemented method of claim 9, wherein incrementing the atleast one occurrence counter when the instance of the event type has aunique characteristic previously unaccounted for in the time seriesbefore the time interval.
 11. The computer-implemented method of claim10, wherein the unique characteristic indicates a unique user beinginvolved in a user action associated with the event type.
 12. Thecomputer-implemented method of claim 1, further comprising adjusting thenumber of the time intervals within the time window based on a degree ofprecision parameter for said classifying of the asset.
 13. Thecomputer-implemented method of claim 1, further comprising adjusting thenumber of the time intervals within the time window based on amount ofavailable data storage in the computer system.
 14. Thecomputer-implemented method of claim 1, wherein computing the firstsignal value includes integrating or summing occurrence countersassociated with the first subset.
 15. The computer-implemented method ofclaim 1, wherein the first subset is a time period encompassing one ormore of the time intervals.
 16. A system, comprising: at least oneprocessor; a memory; a component configured to generate a time series ofoccurrences of an event type associated with at least a data assettracked in a social graph, wherein the time series includes a series ofoccurrence counters and spans a time window that is divided into timeintervals, and the occurrence counters correspond respectively to thetime intervals; wherein at least two of the time intervals are ofunequal lengths; a component to compute a first signal value based on afirst subset of the time series; a component to compute a second signalvalue based on a second subset of the time series, wherein the secondsubset is different from the first subset; and a component to classifythe data asset under a category by comparing the first signal valueagainst the second signal value, the category for indicating to acomputer system to limit or take an action involving the data asset. 17.The system of claim 16, wherein the time intervals areexponentially-decaying time intervals.
 18. The system of claim 16,wherein the memory further comprising a component configured to instructthe at least one processor to provide a value from a first counter ofthe occurrence counters associated with a first time interval to asecond counter of the occurrence counters associated with a second timeinterval.
 19. A computer storage medium storing computer-executableinstructions that, when executed, cause a computer system to perform acomputer-implemented method, the instructions comprising: instructionsfor generating, by a computer system, a time series of occurrences of anevent type associated with at least an asset trackable by the computersystem, wherein the time series includes a series of occurrence countersand spans a time window that is divided into time intervals, and theoccurrence counters correspond respectively to the time intervals;instructions for computing, by the computer system, a first signal valuebased on a first subset of the time series; instructions for computing asecond signal value based on a second subset of the time series, whereinthe second subset is different from the first subset; and instructionsfor classifying, by the computer system, the asset based on the firstsignal value and the second signal value according to a machine learningmodel or a decision tree.
 20. The computer storage medium of claim 19,wherein generating the time series includes representing the time seriesas a curve function capable of integration.